There is a large demand for thin films for use in optical and optical-electronic devices, as insulating and diffusion barriers in silicon-on-insulator electronic devices, chemical sensors, MEMs, pyroelectrics and superconducting films among others. New materials and new approaches to material deposition are constantly being developed to meet just such specific needs in industry and research, For every new materials need, typically, there is one method which is optimal with respect to quality and cost. Therefore, it is beneficial to investigate new types of deposition systems.
The present pulsed arc molecular beam deposition (PAMBD) apparatus was developed to deposit high quality thin films of materials upon substrates within a vacuum chamber. The system is based upon a cluster ion source developed by Siekmann et al. (Z. Phys. D: At., Mol. Clusters 20, 417 (1991) a pulsed arc cluster ion source which has been used primarily as an ion source for the mass spectrometric study of metal cluster ions. The PAMBD source was developed as an inexpensive alternative to reactive pulsed laser deposition (PLD) to produce a variety of metal containing films, such as metal oxide films, that will be the primary topic of the present discussion.
To produce these films and powders, a reactive or non-reactive gas is pulsed between a pair of electrodes situated within a vacuum chamber. A storage capacitor is discharged between the electrode pair during the gas pulse. A substrate is placed inline with the gas pulse, on which an film or powder of the electrode material is then coated. The cathode electrode surface is ablated creating a plasma plume of the cathode material. Gas is pulsed across the rod synchronously with the discharge pulse. The gas serves as a carrier to direct and transport the ablated material to the substrate. As will be discussed in detail, metal, metal nitride, metal oxide, metal carbide, metal halide, carbon, silicon and metal/carbon/silicon composite films can be generated by PAMBD. The gas can be either chemically inert, to produce pure cathode material films, or chemically reactive, to produce chemical compounds of the cathode material. A specific difference of the present processes to PLD is that the gas flow is designed to always sweep clean the source region, whereas in PLD, any process gases are diffused throughout the reactor and are a source of beam diffusion and memory effects.